In some applications, a high-pressure gas tank may be mounted on a moving body, such as a fuel cell vehicle, and there is accordingly a demand to reduce the weight of the high-pressure tank. The manufacturing method of the high-pressure gas tank by filament winding method (hereinafter referred to as “FW method”) is known as one method of reducing the weight of the high-pressure gas tank (see, for example, PTL1). The manufacturing method of the high-pressure gas tank by the FW method winds reinforcement fibers impregnated with a thermosetting resin, such as an epoxy resin, on the outer periphery of a resin tank vessel called liner and then thermally cures the thermosetting resin of the reinforcement fibers to form a fiber-reinforced resin layer.
In the FW method, however, during the thermal curing process of the thermosetting resin, the air contained inside the thermosetting resin or between the reinforcement fibers may gradually move outward to form air bubbles and cause resulting irregularities on the surface of the fiber-reinforced resin layer. The irregularities caused by the air bubbles on the surface layer of the high-pressure gas tank may cause the dimension error of the high-pressure gas tank and the resulting poor assembly of the high-pressure gas tank. Such irregularities on the surface layer may also adversely affect the aesthetic appearance of the high-pressure gas tank.